It looked a bit mournful, that pot of pesto in the fridge door. I had opened it to plop on some pasta a week earlier, used a third of the jar, and then forgotten all about it. Yes, I have made my own in the past, but I don't have the quantity or quality of basil required on hand all the time. Nor, I suspect, do most people. And so occasionally I secrete a pot of commercial pesto into my shopping bag. The other day, I secreted several pots of widely available brands to test them out. Here are the results of my research:

Asda Too fine and gritty; low-grade oil

Bertolli Very salty; no basil flavour; what are green beans doing in it?

The trouble is, I don't often use up a pot in one go. Hence the melancholy survivor in the fridge. It had lost some of its colour and lustre, but not much of its flavour (I dipped in a finger and sucked it, if you must know). Normally I am a stickler for proper use of condiments such as pesto - after all, the people who invented the stuff worked out what it's good for several hundred years ago - but in the interests of thrift, I came up with a few other dishes that make use of its brilliant herby, oily, cheesy astringency.

Recipes serve four.

Griddled chicken breast, aubergine and pesto

Simple, light, quick, delicious - what more do you want? Please don't say healthy. OK, yes, it is that, too. If you don't have a griddle, grill or fry the chicken and aubergine.

Heat the griddle until smoking, lay on the breasts and leave for six minutes. Turn and leave for another six minutes. Transfer to a warm oven to rest.

Slice the aubergines lengthways into slices about as thick as your finger - you need eight slices in all. Place on the griddle, cook for three minutes, turn and repeat on the other side.

Spread one side of each aubergine slice with a decent helping of pesto - a teaspoonful, say. Place a chicken breast on top and lay another pesto-covered aubergine slice on top. Dribble a little oil over and around the plate and serve - it goes very well with this rather nifty tomato accompaniment.

Heat the oil in a saucepan and fry the shallots until soft and golden. Add the tomatoes and warm through - no more. Season and stir the basil leaves through. Serve on the side or even on top of chicken and aubergine stack.

Prawn, cannellini bean, celery and pesto salad

It is essential to use prawns that have some flavour. After much experimentation, and with some regret, I have come to the conclusion that the only prawns readily available to fulfil this criterion are Atlantic prawns with their shells on. I say with regret because it means you have to peel the wretched things. Go easy with the pesto here: you don't want to blot out the other flavours.

Put the beans, celery and prawns in a bowl. Stir in the pesto until everything is lightly coated. Divide among four plates. Roughly chop the celery leaves and sprinkle over for decorative effect. Dribble a little oil around it all.

Minestrone al pesto

Or an Italian version of soupe au pistou, the Provençal equivalent of pesto which is pesto without the pinenuts and pecorino.

Pour two tablespoons of oil into a large saucepan. Add the onion and leek, and fry until soft. Add the carrots, potatoes, celery, tomatoes, bouquet garni and a litre of water, bring to the boil and simmer for 15 minutes. Add the beans and pasta, and simmer for 10 minutes more. Add the courgettes and simmer for another five minutes.

Season, dribble a little oil over the surface of the soup and it is ready. Serve the pesto separately in a bowl, for people to help themselves to as much or as little as they fancy.

Ricotta and pesto spread

Not really a recipe, but it's a neat idea.

3-4 tsp pesto150g ricotta

Stir the pesto into the ricotta. Spread on thin crostini or savoury biscuits.